CN115391886A - Segment-to-segment stress analysis system and method for super-large-diameter shield tunnel structure - Google Patents
Segment-to-segment stress analysis system and method for super-large-diameter shield tunnel structure Download PDFInfo
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Abstract
The invention discloses a segment inter-ring stress analysis system and a segment inter-ring stress analysis method for an oversized-diameter shield tunnel structure, wherein the segment inter-ring stress analysis system comprises a segment internal stress acquisition unit, a segment inter-ring stress acquisition unit and a dissipation rule analysis unit, wherein the segment internal stress acquisition unit comprises a plurality of groups of steel bar dynamometers which are positioned on longitudinally pre-embedded force measurement steel bars of each segment; the inter-segment stress acquisition unit comprises a liner and a force measurement thimble. According to the method, through an air shaft in-situ full-scale model test, a dissipation process rule of longitudinal force transmission between shield segment rings can be obtained, so that the problems that stress distribution between the rings is not clear, the dissipation rule is difficult to obtain and the like are solved, the segment is prevented from being damaged during assembling, the problems that opening and staggering are caused by segment stress dissipation after a jack is retracted and the like are solved, and in addition, a large amount of data are provided in the test, so that the defect that the value of segment design parameters has certain randomness and blindness is overcome.
Description
Technical Field
The invention belongs to the technical field of shield tunnel construction, and particularly relates to a segment-to-segment stress analysis system of an ultra-large diameter shield tunnel structure, and also relates to a segment-to-segment stress analysis method of the ultra-large diameter shield tunnel structure.
Background
In recent years, with the continuous advance of national development strategy and infrastructure construction and the further improvement of high-speed rail network, expressway network and urban road network structures, more and more large-diameter shield tunnel projects are produced. Although the current super-large diameter shield tunnel is widely applied, the super-large diameter shield tunnel is still in a 'extensive' construction and operation state at present, the problems generated in the construction and operation processes of the super-large diameter shield tunnel are more and more, such as the problems of the fragmentation of a shield tunnel segment structure, the opening of a joint, the wrong station and the like are also frequently generated, and great threats are brought to the construction safety and the structure service performance of the shield tunnel.
Aiming at the problems, the adopted methods mainly comprise means such as numerical analysis, model test, field monitoring and the like, however, the adopted methods cannot truly reflect the segment-to-ring stress of the tunnel structure of the super-large-diameter shield under the actual working condition, and are mainly reflected as follows:
(1) Selection basis of key design parameters of super-large-diameter shield tunnel structure is lacked
Due to the existence of the shield segment ring and the longitudinal joint, the difference between the stress characteristic of the segment structure and the common reinforced concrete structure is obvious, and the shield tunnel structure design method is mainly applied to a correction conventional method and a beam-spring model. The rigidity reduction coefficient in the correction method and the bending moment improvement coefficient in the staggered joint assembly have great influence on the accuracy of calculating the deformation and the internal force of the duct piece; the joint stiffness coefficient in the beam-spring model determines the accuracy of a calculation result, which is an important reason that the beam-spring model is not widely popularized in China, and is mostly a three-ring assembled model, and stratum-structure response data under an in-situ condition is lacked, so that the value of a segment design parameter has certain randomness and blindness;
(2) Longitudinal force transfer mechanism between pipe sheet rings under action of shield jack and dissipation rule are not clear
In the aspect of research on longitudinal stress of shield tunnel segments, the research is mostly focused on the influence of adverse factors such as stratum deformation, load change and earthquake, the longitudinal analysis of the whole tunnel structure is carried out, for example, the research on the problems of longitudinal stress, deformation, annular seam opening and the like of the tunnel is carried out by utilizing a longitudinal equivalent serialization model and a longitudinal foundation beam-spring model, and the attention points of the research are mostly focused on the longitudinal response of the tunnel in the operation stage. However, in actual construction, the problems of cracking, joint opening, slab staggering and the like of a shield tunnel segment structure frequently occur during tunnel construction, which are closely related to a force transmission mechanism between segment rings under the action of a jack, and although a mode of fine numerical calculation can be adopted to obtain longitudinal force transmission and a dissipation rule between the related segment rings, the joint of every two adjacent segment rings bears the combined action of axial force, shearing force and bending moment, springs and contact units with different properties are needed, so that the subjectivity is high, and the stress characteristic in a real state cannot be reproduced, therefore, the stress distribution and the dissipation rule between the rings are difficult to obtain, and the problems of breakage during segment assembly, opening caused by segment stress dissipation after the jack is retracted, slab staggering amount and the like caused by the difficult problems cannot be solved.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide an improved inter-segment-ring stress analysis system of an oversized-diameter shield tunnel structure.
Meanwhile, the invention also relates to a segment-to-segment stress analysis method of the shield tunnel structure with the ultra-large diameter.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: the utility model provides a section of jurisdiction is stress analysis system between ring of super large diameter shield tunnel structure, its is used for in the air shaft normal position full scale model test, and keeps obtaining under the shield structure jack effect and has assembled the section of jurisdiction ring or treat the stress of assembling the section of jurisdiction, and section of jurisdiction is stress analysis system between ring includes:
the device comprises a duct piece internal stress acquisition unit, a plurality of shield jacks and a plurality of duct piece internal stress acquisition units, wherein the duct piece internal stress acquisition unit comprises a plurality of groups of reinforcing steel dynamometer positioned on longitudinally pre-embedded force measurement reinforcing steel bars of each duct piece, the plurality of groups of reinforcing steel dynamometer are distributed at intervals along the arc length of the duct piece, a plurality of reinforcing steel dynamometer are arranged in each group, the reinforcing steel dynamometers are aligned with the abutting end surfaces of the shield jacks and distributed at intervals inwards, and the stress level in the duct piece under the action of the shield jacks is fed back through the reinforcing steel dynamometer;
the stress acquisition unit between the segment rings comprises a liner which is similar to the longitudinal splicing end face of the segment in shape and is attached to the longitudinal splicing end face of the segment, and a plurality of force measurement thimbles which extend along the abutting direction of a shield jack, wherein one end of each force measurement thimble is embedded in the segment, the other end of each force measurement thimble penetrates through the liner and abuts against the spliced segment, and the stress between the corresponding segment or segment ring is acquired through the compression amount of the liner under the acting force of the shield jack;
and the dissipation rule analysis unit is respectively in signal communication with the steel bar dynamometer and the force measuring thimble and is used for acquiring the stress distribution and the dissipation rule among the rings of the tunnel structure according to the acquired stress.
Preferably, the section of jurisdiction is divided into N section on vertical, and every section equals and forms N +1 segmentation face, every group the reinforcing bar dynamometer corresponds the setting on the segmentation face, and is located the shield jack conflict terminal surface and the M individual segmentation face of section of jurisdiction, and wherein M is the segmentation face at the middle part place of N section.
Preferably, there are a plurality of the longitudinally embedded force measurement steel bars of the duct piece, and the duct piece rings are distributed in an arc shape in the middle of the duct piece rings, wherein a group of steel force meters are correspondingly arranged on the longitudinally embedded force measurement steel bars of each duct piece.
Furthermore, a plurality of segments are longitudinally embedded with force measuring steel bars to form a plurality of concentric arc rows, wherein the arc rows are uniformly distributed in the thickness direction of the segments at intervals.
According to a specific implementation and preferable aspect of the invention, the shield jacks correspond to the longitudinally embedded force measuring bars of the duct piece one by one and abut against the force measuring meter.
Preferably, the length of the longitudinal embedded force measuring steel bars of each segment is at least 3/4 of the longitudinal length of the segment.
Preferably, each segment is longitudinally embedded with a force measuring steel bar, and the end part of the force measuring steel bar is aligned with the abutting end face of the shield jack of the segment.
According to another specific implementation and preferable aspect of the invention, the gasket is made of rubber and has a thickness of 4-10 mm, wherein the stress between the corresponding segments or segment rings is obtained by the compression of the rubber under the action of the shield jack.
According to a specific implementation and preferred aspect of the invention, each segment ring comprises N arc-shaped segments which are spliced end to end, wherein N is more than or equal to 6 and is an integer; every arc section of jurisdiction has first arc terminal surface and second arc terminal surface, first arc terminal surface is for the conflict terminal surface with the shield structure jack contact, second arc terminal surface is for assembling the terminal surface, section of jurisdiction stress acquisition unit still includes soil pressure gauge, displacement meter between rings, the liner is tiled everywhere the terminal surface of assembling of arc section of jurisdiction, soil pressure gauge with the displacement meter all sets up assembling the terminal surface, and can follow the compressive capacity of liner under the shield structure jack effort acquires the stress between rings and the relative displacement of two corresponding section of jurisdiction rings, dissipation law analytical element respectively with dynamometry thimble, soil pressure gauge and displacement meter information intercommunication, and according to the stress and the displacement data that acquire in order to acquire tunnel structure stress between rings and dissipation law.
Preferably, the gasket is made of rubber and has a thickness of 4-10 mm. The liner material is rubber (the butyronitrile cork rubber liner of pasting), and thickness is 5mm, wherein obtains the inter-annular stress of corresponding section of jurisdiction or section of jurisdiction ring through the compressive capacity of rubber under the shield structure jack effort.
Preferably, the gasket is mounted on the pack end face in a shape similar to the shape of the pack end face and aligned from the center. The gasket not only can play the effect that the stress of being convenient for was accurately acquireed, but also can strengthen sealed to a certain extent, reduces opening, the mistake platform volume of section of jurisdiction ring simultaneously and phenomenon emergence probability such as too big.
According to a specific embodiment and preferred aspects of the present invention, the four force-measuring pins are arranged at four corners of the pad, and the earth pressure gauge and the displacement gauge are arranged in an area defined by the four force-measuring pins. And the interference among the force measuring points is avoided, so that the accuracy of stress acquisition is accurate.
According to yet another specific implementation and preferred aspect of the invention, the soil pressure gauge is partially located within the arcuate duct and partially located within the liner, the displacement gauge extends out of the liner and has an outer end surface that is flush with an outer end surface of the liner, wherein the displacement gauge is capable of monitoring longitudinal and radial displacement of the duct collar. That is, the liner can also protect the soil pressure gauge and the displacement gauge, and prolong the service life, so as to facilitate the acquisition of stress.
Preferably, the displacement meter is a plurality of vibration wire type displacement meters, and the plurality of vibration wire type displacement meters are distributed at intervals along the arc-shaped central line of the assembled end face.
Furthermore, the soil pressure meters are arranged in a plurality of areas, and are staggered with the displacement meters at intervals in the areas where the arc-shaped center lines of the assembled end surfaces are located. Reasonable layout and more accurate acquisition of required data.
In addition, N =6, and a segment ring is composed of one capping block (F) -shaped segment, two adjacent blocks (L1, L2), and six standard blocks (B1, B2, B3, B4, B5, B6). Due to the arrangement, stress and displacement data are acquired more effectively, and assembling of the pipe sheet rings is facilitated (especially for a tunnel structure of a shield with an ultra-large diameter).
Preferably, the segment inter-ring stress acquisition unit further comprises a fiber grating displacement meter arranged at the splicing position of every two adjacent segment rings, wherein the fiber grating displacement meter is provided with two connecting ends, the two connecting ends are respectively fixed with the two assembled arc-shaped segments, and the fiber grating displacement meter acquires the longitudinal displacement between the two assembled adjacent segment rings. In this way, not only can the necessary data be obtained at the splice gap, but also the longitudinal displacement amount can be further effectively obtained by the external fiber grating displacement meter of the tube sheet loop.
Furthermore, a plurality of fiber grating displacement meters are uniformly distributed on the inner wall of the pipe sheet ring around the circumferential direction of the pipe sheet ring, wherein at least one fiber grating displacement meter is distributed on each arc-shaped pipe sheet.
In addition, the shield segment ring stress analysis system further comprises soil pressure boxes, flexible soil pressure gauges, a concrete strain gauge, a bolt axial force gauge and an annular steel bar stress gauge, wherein the soil pressure boxes and the flexible soil pressure gauges are uniformly distributed on the outer side of the segment ring at intervals along the circumferential direction of the segment ring, and two soil pressure boxes are distributed between every two adjacent flexible soil pressure gauges; the concrete strain gauges are distributed in the middle and at two ends of each arc-shaped duct piece; the annular steel bar stress meter is arranged close to the concrete strain meter in the middle; the bolt axial force meters are distributed at the longitudinal seams of the segment rings.
The other technical scheme of the invention is as follows: a segment-to-ring stress analysis method of an ultra-large diameter shield tunnel structure adopts the segment-to-ring stress analysis system of the ultra-large diameter shield tunnel structure, and comprises the following steps:
s1, acquiring the internal stress of the duct piece, wherein the internal stress is acquired by a plurality of groups of steel bar force gauges;
s2, acquiring inter-segment stress, namely acquiring the inter-segment stress of a corresponding segment or segment ring through a force measuring thimble by using the compression amount of the liner under the acting force of a shield jack;
and S3, acquiring the stress distribution and dissipation rule among the rings of the tunnel structure, and screening and analyzing the data based on the data acquired by the S1 and the S2.
Due to the implementation of the technical scheme, compared with the prior art, the invention has the following advantages:
according to the invention, through an air shaft in-situ full-scale model test, the longitudinal stress between the segment rings and the internal stress of the segment can be obtained under the action of construction elements such as shield jack thrust, segment assembling mode and the like, and the dissipation process rule of the longitudinal force transmission between the shield segment rings is obtained, so that the problems of unclear distribution of the stress between the rings, difficulty in obtaining the dissipation rule and the like can be solved, the damage of the segment during assembling can be avoided, the problems of opening, overlarge staggering amount and the like caused by segment stress dissipation after the jack is retracted can be solved, and in addition, a large amount of data is provided in the test, so that the defect that the value of the segment design parameters has certain randomness and blindness can be overcome.
Drawings
FIG. 1 is a schematic view (simplified) of the operating principle of the segment-to-segment stress analysis system of the present invention;
FIG. 2 is a schematic view of the arrangement of segment internal force monitoring points of the present invention;
FIG. 3 is a schematic diagram of circumferential arrangement of a reinforcing bar dynamometer on longitudinally embedded force-measuring reinforcing bars of a duct piece;
FIG. 4 is a schematic view of the arrangement meter of the longitudinal reinforcing bar dynamometer of the present invention (facing the jack side);
FIG. 5 is a schematic view of the arrangement of a force measuring thimble according to the present invention (facing the jack side);
FIG. 6 is a schematic view of the arrangement of the combination of the longitudinal steel bar stress gauge and the force measuring thimble of the present invention (on the side facing the jack);
FIG. 7 is a schematic front view of a shield segment ring stress analysis system of the present invention;
FIG. 8 is a schematic axial view of the segment rings of FIG. 7;
FIG. 9 is a schematic structural view of the segment of FIG. 8;
FIG. 10 is a schematic view of an assembled end surface of the segment of FIG. 9;
FIG. 11 is a schematic view showing the distribution of the earth pressure around the tunnel according to the present invention;
FIG. 12 is a schematic view showing the distribution of loads of the present invention along the longitudinal direction of the tunnel;
wherein: A. a segment inter-ring stress acquisition unit; a1, a gasket; a2, a force measuring thimble; a3, a soil pressure gauge; a4, a displacement meter; a5, a fiber bragg grating displacement meter;
B. a dissipation law analysis unit;
g. an arc-shaped duct piece; g1, a first arc-shaped end face; g2, a second arc-shaped end face.
H. A tube sheet ring; J. an air shaft; D. shield jack (jack).
Detailed Description
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiment in many different forms than those described herein and those skilled in the art will be able to make similar modifications without departing from the spirit of the application and therefore the application is not limited to the specific embodiments disclosed below.
As shown in fig. 1 to 10, the segment-to-segment stress analysis system of the large-diameter shield tunnel structure of the embodiment is used for an air shaft in-situ full-scale model test, and keeps the shield jack to obtain the stress of the segment rings which are assembled or the segments to be assembled.
Specifically, a blocking form of "6+2+1" is adopted, namely the blocking type duct piece consists of 1 top sealing block (F) type duct piece, 2 adjacent blocks (L1 and L2) and 6 standard blocks (B1-B6).
The corresponding ring numbers of the air shaft in-situ full-scale model test are 1306-1313 rings and 1314-1321 rings respectively, wherein the main test ring is selected according to the principle of symmetry and center, two rings at the boundary of the end are removed, ring numbers 1309, 1312, 1315 and 1318 are sequentially selected as the main test ring at the position of 5 equal divisions of the test area, wherein two stratum divisions respectively occupy two rings, four rings are counted, and the rest rings are used as auxiliary test rings.
In this example, taking the main test ring as an example, the shield segment ring stress analysis system includes a segment internal stress acquisition unit, a segment inter-ring stress acquisition unit, and an dissipation law analysis unit.
The duct piece internal stress acquisition unit comprises a plurality of groups of steel bar dynamometers positioned on longitudinal embedded force measuring steel bars of each duct piece, wherein the steel bar dynamometers are arranged at the steel bar positions within the range of 1m in the longitudinal depth of the boss positions at the side, facing the jack, of the duct piece so as to acquire space distribution data of the duct piece along the longitudinal stress under the thrust action of the jack.
Specifically, 2 rows of measuring points are uniformly distributed on the F-shaped segment in the circumferential direction, and 3 rows of measuring points are uniformly distributed on the B-shaped segment and the L-shaped segment in the circumferential direction; the F blocks, the B blocks and the L blocks are all arranged in 3 columns along the longitudinal direction.
Every reinforcing bar dynamometer has 3, and aligns inside interval distribution from section of jurisdiction and shield jack conflict terminal surface, feeds back the stress level of section of jurisdiction inside under the jack effect through the reinforcing bar dynamometer simultaneously.
The longitudinal length of the tube sheet is 2000mm, the thickness is 650mm, and the distance between the longitudinal arrangement of the tube sheet is 500mm.
The length of each segment longitudinal embedded force measurement steel bar is 1550mm, and each segment longitudinal embedded force measurement steel bar is aligned with the abutting end face of the shield jack of the segment from the end part.
The vertical pre-buried dynamometry reinforcing bar of section of jurisdiction has 6, and is circular for being the arc distribution in with the section of jurisdiction ring, wherein corresponds on the vertical pre-buried dynamometry reinforcing bar of every section of jurisdiction and is equipped with a set of reinforcing bar dynamometer.
The vertical pre-buried dynamometry reinforcing bar of 6 root canal pieces forms the arc row of 2 concentric centers, and wherein 2 arc rows are at the even interval distribution of section of jurisdiction thickness direction, and shield structure jack and the vertical pre-buried dynamometry reinforcing bar one-to-one of section of jurisdiction simultaneously, and contradict on the reinforcing bar dynamometer.
Referring to fig. 7 to 10, in this example, a segment ring H is formed by one capping block (F) -shaped segment, two adjacent blocks (L1, L2), and six standard blocks (B1, B2, B3, B4, B5, B6). Due to the arrangement, stress and displacement data are acquired more effectively, and the assembly of the pipe sheet rings is facilitated (particularly for a tunnel structure of a shield with an ultra-large diameter).
In this example, taking the standard block B1 as an example, the arc-shaped duct piece g has a first arc-shaped end surface g1 and a second arc-shaped end surface g2, the first arc-shaped end surface g1 is an abutting end surface contacting with the shield jack D, and the second arc-shaped end surface g2 is an assembling end surface.
In this example, the shield segment ring stress analysis system includes a segment inter-ring stress acquisition unit a and an dissipation law analysis unit B.
The segment inter-ring stress acquisition unit A comprises a liner a1, a force measurement thimble a2, a soil pressure gauge a3, a displacement meter a4 and a fiber grating displacement meter a5.
The gasket a1 is mounted on the assembly end face in a shape similar to the assembly end face and aligned from the center. The gasket not only can play the effect that the stress of being convenient for was accurately acquireed, but also can strengthen sealed to a certain extent, reduces opening, the mistake platform volume of section of jurisdiction ring simultaneously and phenomenon emergence probability such as too big.
In this example, the liner a1 is made of rubber (bonded nitrile cork rubber liner) and has a thickness of 5mm, wherein the inter-ring stress of the corresponding segment or segment ring is obtained by the compression of the rubber under the action of the shield jack D.
Four force measurement thimbles a2 are provided, one end of each force measurement thimble is pre-embedded in the arc-shaped duct piece g, and the other end penetrates out of the liner a1 and is abutted on the assembled duct piece.
Four force measuring thimble a2 are distributed at four corners of the pad a 1.
Soil pressure gauge a3 and displacement meter a4 all set up and are assembling the terminal surface, and can obtain the stress and relative displacement between the ring of two section of jurisdiction rings H that correspond along with liner a1 under the shield structure jack d effort.
The soil pressure gauge a3 and the displacement gauge a4 are distributed in the area formed by the four force measuring thimbles. And the interference among the force measuring points is avoided, so that the accuracy of stress acquisition is accurate.
The soil pressure gauge a3 is partially positioned in the arc-shaped segment inner part and positioned in the liner a1, the displacement meter a4 penetrates out of the liner, the outer end face of the displacement meter a4 is flush with the outer end face of the liner a1, and the displacement meter a4 can monitor the longitudinal and radial displacements of the segment ring H. That is, the liner can also protect the soil pressure gauge and the displacement gauge, and prolong the service life, so as to facilitate the acquisition of stress.
The displacement meter a4 is a plurality of vibration wire type displacement meters, and the plurality of vibration wire type displacement meters are distributed at intervals along the arc-shaped central line of the assembled end face.
In this embodiment, a plurality of soil pressure gauges a3 are arranged in the area of the arc center line of the assembled end face at intervals and in a staggered manner with the displacement gauge a 4. Reasonable layout and more accurate acquisition of the required data.
The fiber grating displacement meter a5 is arranged at the splicing position of every two adjacent pipe sheet rings H, wherein the fiber grating displacement meter a5 is provided with two connecting ends, the two connecting ends are respectively fixed with the two assembled arc-shaped pipe sheets, and the fiber grating displacement meter a5 acquires the longitudinal displacement between the two assembled adjacent pipe sheet rings. Thus, not only the necessary data can be obtained at the splice gap, but also the longitudinal displacement amount can be further effectively obtained by the external fiber grating displacement meter of the tube sheet ring.
In this example, there are a plurality of fiber grating displacement meters a5, and the fiber grating displacement meters a5 are uniformly distributed on the inner wall of the segment ring H around the circumference of the segment ring H, wherein at least one fiber grating displacement meter a5 is distributed on each arc-shaped segment.
The dissipation law analysis unit B is respectively in information communication with the force measuring thimble a2, the soil pressure gauge a3 and the displacement gauge a4 and obtains the dissipation law according to the information.
In addition, the shield segment ring stress analysis system further comprises a soil pressure cell, a flexible soil pressure gauge, a concrete strain gauge, a bolt axial force meter and an annular steel bar stress meter.
Soil pressure cell and flexible soil pressure gauge encircle the even interval distribution in section of jurisdiction ring outside around the section of jurisdiction ring, and every adjacent two it has two soil pressure cells to distribute between the flexible soil pressure gauge.
In this example, the total number of the flexible soil pressure gauges and the soil pressure boxes is 12, wherein the number of the flexible soil pressure gauges is 4, and the number of the soil pressure boxes is 8.
The concrete strain gauges are distributed in the middle and at two ends of each arc-shaped pipe piece.
The annular steel bar stress meter is arranged close to the middle concrete strain meter.
The bolt axial force meters are distributed at the longitudinal seams of the segment rings.
In addition, the dissipation rule analysis unit is used for analyzing the data of each stress meter, strain gauge and pressure gauge, and inversion analysis is carried out by combining test data, so that a reasonable segment structure calculation parameter value range and a reasonable segment structure calculation parameter value are summarized.
Then, through an air shaft in-situ full scale model test, the longitudinal stress between the segment rings and the internal stress of the segment can be obtained under the action of construction elements such as wall grouting pressure, shield machine jack thrust, segment assembling mode and the like, and the dissipation process rule of the longitudinal force transmission between the shield segment rings is obtained simultaneously, so that the problems that the stress distribution between the rings is not clear, the dissipation rule is difficult to obtain and the like are solved, the segment can be assembled and damaged, and the problem that the segment stress dissipation is opened and the dislocation amount is too large after the jack is withdrawn.
Meanwhile, in the embodiment, the analysis process of the shield tunnel longitudinal force dissipation law three-dimensional numerical analysis model mainly comprises the following steps:
1. establishing a shield model: and establishing a shield tunnel numerical model of the 16-ring segment through finite element software.
2. Analysis of simulation conditions: the analysis is carried out according to the whole shield construction process, and the special topic selects a load space-time subsection model in two stages of an assembling stage and a separating stage.
3. Main load in construction stage
(1) Thrust of a jack: the method belongs to one of main loads borne by the pipe piece in the shield tunnel construction stage, and is also one of reasons for cracking of the pipe piece in the construction stage, and particularly when the annular seam surface of the pipe piece has construction or manufacturing errors to cause uneven annular seam surface, even if the annular seam surface has a height difference of 0.5-1.0 mm, the next annular pipe piece can generate great splitting moment. Meanwhile, the center of the supporting shoe of the jack is deviated, and the segment can be cracked. In the thematic numerical analysis process, the jack thrust is simplified into a pressure load acting on the annular seam base plate.
(2) Grouting pressure: the distribution is comparatively complicated, and inhomogeneous slip casting pressure can cause section of jurisdiction dislocation, fracture even. The grouting pressure is linearly reduced along the axial direction of the tunnel, and the pressure is finally reduced to be the same as that of the surrounding soil layer. The shield construction at present basically uses a synchronous grouting technology, and the pressure range is 0.4-0.5 MPa.
(3) Surrounding soil layer pressure: the soil pressure action mode of fig. 11 is adopted, wherein P1 is the overlying soil and water pressure at the top of the segment ring, P2 is the soil layer resistance and the vertical water pressure at the bottom of the segment ring, P3 is the lateral soil and water pressure on the horizontal plane at the top of the segment ring, P4 is the lateral soil and water pressure on the horizontal plane at the bottom of the segment ring, and P5 is the dead weight of the segment. And (3) performing simulation calculation by utilizing the contact force between the soil finite element grids in the model and the segment ring finite element grids under the lateral soil body pressure caused by segment ring deformation. And setting the formation conditions according to the backfill soil in the prototype test.
(4) The extrusion force of the shield shell and the shield tail brush on the duct piece is as follows: when the shield machine snakes or needs to turn, the shield machine adjusts the posture. When the attitude control of the shield tunneling machine is not matched with the curve segment or the crawling amount is too large, the shield tail brush or even the shield shell can extrude the duct piece, so that the duct piece is twisted and deformed to form cracks, and the load borne by one section of tunnel can be simplified into a load system as shown in fig. 12 by integrating all the loads.
4. Material model and principal parameter selection
(1) Segment concrete (modulus of elasticity, poisson's ratio, density);
(2) Bolts (modulus of elasticity, poisson's ratio);
(3) Rubber sealing strips and a backing plate adopt a Mooney-Rivlin first-order constitutive model;
(4) Shield shell (modulus of elasticity, poisson's ratio);
(5) Shield tail brush (elasticity modulus, poisson ratio)
(6) Soil layer (elastic modulus, poisson's ratio)
5. And (3) three-dimensional finite element meshing: all parts of the model, namely the duct piece, the bolt, the water stop strip, the backing plate, the shield shell, the shield tail brush and the soil layer, adopt eight-node three-dimensional entity units. The longitudinal seam gasket and the circular seam gasket are connected by a contact method. Contact surfaces are also adopted between the duct piece and the surrounding soil layer and between the duct piece and the shield tail brush to establish contact. And applying initial strain to the three-dimensional solid unit of the simulated bolt to simulate the application of pre-tightening torque to the bolt in construction. The horizontal direction is an X axis, the vertical direction is a Y axis, and the forward direction of the Z axis is the same as the propelling direction of the shield tunneling machine.
6. Calculating and analyzing: and analyzing and summarizing the space distribution and the dissipation rule of the longitudinal stress between the tunnel rings of the shield segments under the action of the jack according to the result file.
The present invention has been described in detail in order to enable those skilled in the art to understand the invention and to practice it, and it is not intended to limit the scope of the invention, and all equivalent changes and modifications made according to the spirit of the present invention should be covered by the present invention.
Claims (10)
1. The utility model provides a section of jurisdiction inter-annular stress analysis system of super large diameter shield tunnel structure, its is used for in the air shaft normal position full scale model test, and keeps obtaining under the shield structure jack effect and has assembled the section of jurisdiction ring or treat the stress of assembling the section of jurisdiction, and its characterized in that, section of jurisdiction inter-annular stress analysis system includes:
the device comprises a duct piece internal stress acquisition unit, a plurality of pipeline piece internal stress acquisition units and a plurality of pipeline piece internal stress measurement units, wherein the duct piece internal stress acquisition unit comprises a plurality of groups of steel bar dynamometer positioned on each longitudinal pre-buried force measurement steel bar of each duct piece, the steel bar dynamometer is distributed at intervals along the arc length of the duct piece, a plurality of steel bar dynamometers are arranged in each group, the steel bar dynamometer is aligned with the abutting end face of a shield jack and distributed at intervals inwards, and the stress level in the duct piece under the action of the shield jack is fed back through the steel bar dynamometer;
the stress acquisition unit between the pipe piece rings comprises a liner which is similar to the shape of the longitudinal splicing end face of the pipe piece and is attached to the longitudinal splicing end face of the pipe piece, and a plurality of force measurement thimbles which extend along the abutting direction of a shield jack, wherein each pipe piece ring comprises N arc-shaped pipe pieces which are spliced end to end, N is not less than 6 and is an integer; each arc-shaped duct piece is provided with a first arc-shaped end face and a second arc-shaped end face, the first arc-shaped end face is a contact end face which is in contact with the shield jack, the second arc-shaped end face is an assembly end face, one end of each force measuring thimble is pre-embedded in the duct piece from the assembly end face, and the other end of each force measuring thimble penetrates through the liner and contacts the assembled duct piece;
and the dissipation rule analysis unit is respectively in signal communication with the steel bar dynamometer and the force measuring thimble and acquires the stress distribution and dissipation rule among the rings of the tunnel structure according to the acquired stress.
2. The segment-to-ring stress analysis system of the ultra-large diameter shield tunnel structure according to claim 1, characterized in that: the section of jurisdiction divides into N section in proper order on vertical, and every section equals, every group the reinforcing bar dynamometer corresponds the setting on the segmental surface, and is located the shield jack conflict terminal surface and the M individual segmental surface of section of jurisdiction, and wherein M is the segmental surface at the middle part place of N section.
3. The segment-to-ring stress analysis system of the ultra-large diameter shield tunnel structure according to claim 2, characterized in that: the longitudinal embedded force measurement reinforcing steel bars of the duct piece are multiple and distributed in an arc shape in the duct piece ring, wherein a group of reinforcing steel bar dynamometers are correspondingly arranged on the longitudinal embedded force measurement reinforcing steel bars of the duct piece.
4. The segment-to-ring stress analysis system of the extra-large diameter shield tunnel structure according to claim 3, characterized in that: the plurality of the segments are longitudinally embedded with the force measuring steel bars to form a plurality of concentric arc rows, wherein the plurality of the arc rows are uniformly distributed in the thickness direction of the segments at intervals, and the length of each segment is at least 3/4 of the longitudinal length of the segment.
5. The segment-to-ring stress analysis system of the extra-large diameter shield tunnel structure according to claim 4, characterized in that: the shield jacks correspond to the longitudinally embedded force measurement steel bars of the duct pieces one by one and abut against the steel bar dynamometer; each segment is longitudinally embedded with force measuring steel bars, and the end parts of the force measuring steel bars are aligned with the abutting end surfaces of the shield jacks of the segments.
6. The segment-to-ring stress analysis system of the ultra-large diameter shield tunnel structure according to claim 1, characterized in that: the section of jurisdiction interannular stress acquisition unit still includes soil pressure gauge, displacement meter, the liner is tiled every the terminal surface of assembling of arc section of jurisdiction, the soil pressure gauge with the displacement meter all sets up and is assembling the terminal surface, and can follow the compressive capacity of liner under shield structure jack effort acquires the interannular stress and the relative displacement of two corresponding section of jurisdiction rings, dissipation law analysis unit respectively with dynamometry thimble, soil pressure gauge and displacement meter information intercommunication, and according to the stress and the displacement data that acquire in order to acquire tunnel structure's interannular stress distribution and dissipation law.
7. The segment-to-ring stress analysis system of the extra-large diameter shield tunnel structure according to claim 6, characterized in that: the gasket is made of rubber and has the thickness of 4-10 mm; the gasket is similar to the assembled end face in shape and is arranged on the assembled end face in a self-centering alignment mode.
8. The segment-to-ring stress analysis system of the extra-large diameter shield tunnel structure according to claim 6, characterized in that: the four force measuring thimbles are distributed at four corners of the liner, and the soil pressure gauge and the displacement gauge are distributed in an area formed by the four force measuring thimbles; and/or the soil pressure gauge is partially positioned in the arc-shaped pipe sheet and partially positioned in the liner, the displacement gauge penetrates out of the liner, and the outer end surface of the displacement gauge is flush with the outer end surface of the liner, wherein the displacement gauge can monitor the longitudinal and radial displacements of the pipe sheet ring; and/or the displacement meters are vibration wire type displacement meters, and the vibration wire type displacement meters are multiple, wherein the multiple wire type displacement meters are distributed at intervals along the arc-shaped central line of the assembled end surface; and/or the soil pressure meters are multiple and are distributed in the area where the arc-shaped center line of the assembled end face is located at intervals in a staggered mode with the displacement meters.
9. The segment-to-ring stress analysis system of the extra-large diameter shield tunnel structure according to claim 6, characterized in that: the inter-segment-ring stress acquisition unit further comprises a fiber grating displacement meter arranged at the splicing position of every two adjacent segment rings, wherein the fiber grating displacement meter is provided with two connecting ends, the two connecting ends are respectively fixed with the two assembled arc-shaped segments, and the fiber grating displacement meter acquires the longitudinal displacement between the two adjacent segment rings after the two assembled arc-shaped segments; and/or the fiber bragg grating displacement meters are arranged in plurality and are uniformly distributed on the inner wall of the tube sheet ring around the circumference of the tube sheet ring, wherein at least one fiber bragg grating displacement meter is distributed on each arc-shaped tube sheet.
10. A segment inter-ring stress analysis method for an ultra-large diameter shield tunnel structure is characterized by comprising the following steps: the inter-segment-ring stress analysis system of the super-large-diameter shield tunnel structure is adopted, and comprises the following steps:
s1, acquiring internal stress of a duct piece, wherein the internal stress is acquired by a plurality of groups of steel bar dynamometers;
s2, acquiring inter-ring stress of the duct piece, namely acquiring the inter-ring stress of the corresponding duct piece or duct piece ring through a force measuring thimble according to the compression amount of the liner under the action force of a shield jack;
and S3, acquiring the stress distribution and dissipation rule among the rings of the tunnel structure, and screening and analyzing the data based on the data acquired by the S1 and the S2.
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| CN202210991224.8A CN115391886B (en) | 2022-08-18 | 2022-08-18 | System and method for analyzing stress between segment rings of oversized-diameter shield tunnel structure |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117540480A (en) * | 2024-01-08 | 2024-02-09 | 中铁南方投资集团有限公司 | Method for calculating stress deformation of tunnel lining structure under shield attitude adjustment |
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| KR20120063257A (en) * | 2010-12-07 | 2012-06-15 | 한국건설기술연구원 | Segment structure of shield tunnel making use of a prestressed steel wire and segment lining system fixing the segment therewith |
| CN209670980U (en) * | 2019-01-03 | 2019-11-22 | 浙江交工集团股份有限公司 | A kind of tunneling shield section of jurisdiction site monitoring system |
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| KR20120063257A (en) * | 2010-12-07 | 2012-06-15 | 한국건설기술연구원 | Segment structure of shield tunnel making use of a prestressed steel wire and segment lining system fixing the segment therewith |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117540480A (en) * | 2024-01-08 | 2024-02-09 | 中铁南方投资集团有限公司 | Method for calculating stress deformation of tunnel lining structure under shield attitude adjustment |
| CN117540480B (en) * | 2024-01-08 | 2024-04-19 | 中铁南方投资集团有限公司 | Method for calculating stress deformation of tunnel lining structure under shield attitude adjustment |
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